Transparent Bitmap (BMP)

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Tue, 21 June 2005 11:03 Go to next message
sandspider (Photoshop begginer)
Hi All,
Nice triky question .
How can we save a image with transparency as a BMP .
This is for use as a visible watermark with Digimarc PictureMarc 2005
which is a image watermarking utility plugin for photoshop.

Thanks
Tue, 21 June 2005 11:34 Go to previous messageGo to next message
RSD99 (Photoshop expert)
The short answer is you can't.

The BMP file format does not "support" transparency.

IIRC: The only formats that are capable of saving transparency (otherwise
known as Alpha channel) ... that are in relatively common usage ... are

GIF
PNG
TIFF (recent variations)
TARGA





"sandspider" <info@sandspider.net> wrote in message
news:1119366236.721155.283820@g43g2000cwa.googlegroups.com...
> Hi All,
> Nice triky question .
> How can we save a image with transparency as a BMP .
> This is for use as a visible watermark with Digimarc PictureMarc 2005
> which is a image watermarking utility plugin for photoshop.
>
> Thanks
>
Tue, 21 June 2005 12:17 Go to previous messageGo to next message
Tacit[1] (Photoshop expert)
In article <1119366236.721155.283820@g43g2000cwa.googlegroups.com>,
"sandspider" <info@sandspider.net> wrote:

> Nice triky question .
> How can we save a image with transparency as a BMP .

Step 1: You can't.

The BMP format does not support transparency.

--
Art, photography, shareware, polyamory, literature, kink:
all at http://www.xeromag.com/franklin.html
Tue, 21 June 2005 12:19 Go to previous messageGo to next message
Tacit[1] (Photoshop expert)
In article <9sWte.773$kZ.476@trnddc02>, "RSD99" <rsdwla.NOSPAM@gte.net>
wrote:

> IIRC: The only formats that are capable of saving transparency (otherwise
> known as Alpha channel) ... that are in relatively common usage ... are
>
> GIF
> PNG
> TIFF (recent variations)
> TARGA

Alpha channels are not the only way to achieve transparency.

GIF doesn't use an alpha channel for transparency; instead, it
designates a color in the color look-up table as transparent.

PNG, TIFF, and Targa formats support alpha transparency.

EPS, TIFF, and (some varieties of) Scitex CT support clipping path
transparency.

--
Art, photography, shareware, polyamory, literature, kink:
all at http://www.xeromag.com/franklin.html
Tue, 21 June 2005 16:33 Go to previous messageGo to next message
Nicholas Sherlock (Photoshop expert)
sandspider wrote:
> Nice triky question .
> How can we save a image with transparency as a BMP .

Some programs will treat a 32-bit bitmap as having an alpha channel, is
this what you mean? Right click on your layer's thumbnail, click "Select
layer transparency". Click the "Select" menu, click "Save selection...".
Save it as a new channel in your picture (Call it whatever you like, I
prefer "Alpha"). Save as bitmap, make sure "Alpha channels" is ticked.

This may be version dependant, I use PhotoShop CS.

Cheers,
Nicholas Sherlock
Tue, 21 June 2005 17:53 Go to previous message
KatWoman (Photoshop expert)
but are any browsers configured to see the alpha in the 32 bit images?
Windows OS can see the transparency.
When I save Tiff with alpha channels Windows only "sees" the top
(adjustment ) layer. It can't see "through" to the rest of the image, of
course in PS they look fine and contain all the layers.

"Nicholas Sherlock" <n_sherlock@hotmail.com> wrote in message
news:d99tk9$htn$1@lust.ihug.co.nz...
> sandspider wrote:
>> Nice triky question .
>> How can we save a image with transparency as a BMP .
>
> Some programs will treat a 32-bit bitmap as having an alpha channel, is
> this what you mean? Right click on your layer's thumbnail, click "Select
> layer transparency". Click the "Select" menu, click "Save selection...".
> Save it as a new channel in your picture (Call it whatever you like, I
> prefer "Alpha"). Save as bitmap, make sure "Alpha channels" is ticked.
>
> This may be version dependant, I use PhotoShop CS.
>
> Cheers,
> Nicholas Sherlock
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